Objectives 1-7 here

Circulation in Animals

1. Describe the need for circulatory and respiratory systems due to increasing animal body size.

As animals increase in size without a respiratory/circulatory system they would be unable to move molecules throughout the body. The respiratory/circulatory system provides extensive surface area so that gases can diffuse quickly due to the short distance required for them to travel. For example, if it takes 1 second for a given quantity of glucose to diffuse 100 um, it will take 100 second for the same quantity to diffuse 1mm and almost an hour to diffuse 1 cm.

2. Explain how a gastrovascular cavity functions in part as a circulatory system. The animals that have a gastrovascular system have (mostly have 2 cell layers) This cavity allows for digestion as well as distribution of substances throughout the organism. Since this cavity is so extensive it can easily serve to take care of the distribution of nutrients. Planaria and other flatworms also have a gastrovascular cavity and in each case the cells are bathed in fluids increasing the rate of diffusion but decreasing the distance substance must travel.

3. Distinguish between open and closed circulatory systems. List the three basic components common to both systems.

The three basic components of open and closed circulatory systems are: a circulatory fluid(blood), a set of tubes(blood vessels) through which the blood moves through the body and a muscle pump(heart)

Open circulatory systems are found in arthropods, most mollusks where blood bathes the organs directly. There is no distinction between blood and interstitial fluid. So the fluid is called hemolymph. There are spaces which surround the organs, called sinuses, the heart pumps the hemolymph to these areas and the organs are bathed. Body movements help to move the fluid and the exchange between the hemolymph and the body tissue is direct.

Closed circulatory systems have vessels that separate the blood from the interstitial fluid and the heart pumps the fluid. Earthworms, squids, octopuses, and vertebrates have a closed circulatory system.

4. List the structural components of a vertebrate circulatory system and relate their structure to their functions.

There are variations on these but for the most part the heart, one or two atrium(plural) that receive blood returning , one or two ventricles, the chambers that pump blood out of the heart. Arteries, veins, and capillaries are the three main kinds of blood vessels. Arteries carry blood away from the heart and veins carry blood to the heart. Arteries--> arterioles --> capillary beds. -->venules -->veins.

The higher the metabolic rate the more complex the circulatory system in an organism. more powerful hearts. Gill circulation in aquatic organisms is another adaptation. Fish have one atria and ventricle. Blood pumped from the ventricle travels first to the gills(gill circulation) where it picks up oxygen and disposes of carbon dioxide across the capillary walls. The gill capillaries converge to a vessel that carries oxygen-rich blood to capillary beds in al other parts of body (systemic circulation). Blood then returns to the atrium via the veins. Oxygen-rich blood leaving the gills flows to the systemic circulation quite slowly(although the process is aided by body movements during swimming) This constrains the delivery of oxygen to body tissues and hence the maximum aerobic metabolic rate of fishes.

Frogs and other amphibians have a three chambered heart- two atria and one ventricle. The ventricle pumps blood into a forked artery that splits the ventricle's output into the pulmocutaneous and systemic circulations. Pulmocutaneous circulation lead to the capillaries in the lungs and skin of a frog. Blood picks up oxygen and releases CO 2 before returning oxygen-rich blood is pumped into the system circulation which supplies all body organs &then returns oxygen-poor blood to the right atrium via the veins. This is double circulation. Since most of the oxygen-rich blood is pumped into the systemic circulation, which supplies all body organs and then returns oxygen-poor to the right atrium via the veins. This provides a vigorous flow of blood to the brain, muscles, and other organs because the blood is pumped a second time after it looses pressure in the capillary beds of the lungs or skin. In the ventricle there is some mixing of oxygen-rich and oxygen-poor blood. There is a ridge in the ventricle that diverts most blood.

Reptiles have a 3-chambered heart, the ventricle is partially divided. They have less mixing of oxygenated and deoxygenated blood than amphibians.

In reptiles(crocodiles and alligators) and all birds and mammals there is complete separation of oxygenated and deoxygenated blood and there are 4 chambers in the heart.

5. Describe the general relationship between metabolic rates and the structure of the vertebrate circulatory system. Ectotherms require a great deal less energy to power their systems. Endotherms on the hand require about 10X as much as their ecothermic counterparts. So have large powerful hearts works for the endotherm.

6. Distinguish between pulmonary and systemic circuits and explain the functions of each. The pulmonary circuit cares blood from the heart to the lungs and back to the heart. The actual path is as follows:

1. The right ventricle pumps blood to the lungs via

2. the pulmonary arteries

3. as the blood flows through capillary beds in the right and left lungs, it loads with oxygen and unloads carbon dioxide. Oxygen-rich blood returns from the lungs via the pulmonary veins

4. to the left atrium of the heart

5. Oxygen-rich blood flows into the left ventricle, as the ventricle opens and the atrium contracts. The left ventricle pumps the oxygen –rich blood out to the body tissues through the systemic circuit.

6. blood leaves the left ventricle via the aorta

(which conveys blood to arteries leading throughout the body.

7. The first branches from the aorta are the coronary arteries which supply blood to the heart muscle. Then come branches leading to capillary bed in the head and arms

8. The aorta continues in a posterior direction, supplying oxygen-rich blood to arteries leading to arterioles and capillary bed in the abdominal organs and legs.

9.Capillaries rejoin to form venules, which convey blood to veins. Oxygenated poor blood from the head, neck, and forelimbs is channeled into a large vein called the anterior (or superior) vena cava.

10. Another large vein called the posterior (or inferior) drains blood from the trunk and hind limbs. The two venae cavae empty their blood into
the right atrium, from which the oxygen-poor blood flows into the right ventricle.

7.Explain the advantage of double circulation over a single circuit.

The advantage of double circulation is increased cardiac out put and stroke volume.(the amount of blood pumped by the left ventricle in the each contraction


Using diagrams, compare and contrast the circulatory schemes of fish, amphibians, reptiles, birds, and mammals.

Simpler organisms, like bugs and worms, don't have lungs or gills. Gasses diffuse directly through the skin into the blood.
All of the organisms below (vertebrates) have a closed circulatory system, meaning that the blood stays within the veins and arteries.

Here is a general picture of fish, amphibian, and mammal blood-flow:


Fish - Single circuit bloodflow with a two chambered heart. It's not very powerful: one ventricle and one atrium.
1. Ventricle
2. Gill capillaries (gas exchange)
3. Rest of the body (body capillaries)
4. Atrium

Because the blood has to travel through two sets of capillaries on a single circuit, bloodflow is relatively slow in fish, limiting their metabolic rate.

Amphibians - Three-chambered heart and two circuits of blood flow: pulmocutaneous and systemic. This double circulation delivers blood to systemic organs under high pressure. In the single ventricle, there is some mixing of oxygen-rich blood with oxygen-poor blood.

Reptiles - Most reptiles have a circulatory system similar to amphibians with a three chambered heart. There are however exceptions, such as the crocodile, with a four chambered heart.


Birds and Mammals - Birds and mammals have a powerful four chambered heart.

The valves prevent backflow of blood. The aorta is the artery that pumps blood to the rest of the body and has the highest pressure. The vena cava is the opposite: it receives blood from the rest of the body and is the region of lowest pressure in the circulatory system. The pulmonary artery and veins bring blood to and from the heart, respectively.


Blood flows like so:
1. Vena cava
2. Right atrium
3. Tricuspid (right atrioventricular) valve
4. Right ventricle
5. Pulmonary semilunar valve
6. Pulmonary artery
7. Lungs
8. Pulmonary vein
9. Left atrium
10. Bicuspid (left atrioventricular) valve
11. Left ventricle
12. Aortic semilunar valve
13. Aorta
14. Rest of the body
15. Back to the vena cava

Objectives 9-27 here

9: Define a cardiac cycle, distinguish between systole and diastole, and explain what causes the first and second heart sounds.
Patrick Doran

The cardiac cycle is one complete sequence in which the heart pumps oxygenated blood out to the body and then refills with deoxygenated blood. This cycle consists of two phases, systole and diastole. Systole is when the heart contracts to pump blood out to the body. Diastole is when the heart relaxes to fill with blood again. The first heart sound on a stethoscope, "lub", occurs during systole and is caused by the reverberation of blood against the closed atrioventricular (AV) valves. The AV valves close during systole to prevent blood from being pushed back into the atria when the ventricles contract to pump blood out to the lungs in the case of the right ventricle or the body in the case of the left ventricle. Some blood is pushed against these valves by the contraction of the ventricles causing the first heart sound. The second sound on a stethoscope "dub" occurs during diastole and is made by the recoil of blood against the semilunar valves. This recoil happens because at the end of systole and the beginning of diastole, the ventricles are empty. This means the ventricles have a lower pressure than the pulmonary artery in the case of the right ventricle and the aorta in the case of the left ventricle. This would naturally cause the reversal of flow back into the ventricles if it weren't for the pulmonary and aortic valves, which close when the pressure difference is created at the beginning of diastole. When these valves close, the pressure difference still causes blood to recoil against them, causing the second heart sound.

10. Define cardiac output and describe two factors that influence it. (A.Gosiewski)
Cardiac output is the volume of blood per minute thhat is pumped by the left ventricle into the systematic circuit. Two factors that influence this are heart rate, the rate of contraction or the number of beats per minute, and stroke volume, the amount ofblood pumped by the left ventricle in each contraction.

13. Define pacemaker and describe the location of two patches of nodal tissue in the human heart. (Nicole Saitta)

The pacemaker is a specialized region of the right atrium of the heart that sets the rate of contraction. It is also called the sinoatrial (SA) node. This SA node is found in the wall of the right atrium near where the superior vena cava enters the heart. It maintains the heart’s pumping rhythm by setting the rate at which all cardiac muscles contract. The second nodal tissue is the atrioventricular (AV) node. This node is found in the wall between the right atrium and the right ventricle. It delays the electrical signal to ensure that the atria wall will contract first and empty completely before the ventricles contract.

14.Describe the origin and pathway of the action potential (cardiac impulse) in the normal human heart. Giselle Ilada

Heart cells maintain its rhythmic beat involuntarily. They continue to contract even without any signal from the nervous system. First the SA node, or pacemaker, sets the rate and timing at which the cells contract. This is located in the wall of the right atrium where the superior vena cava enters. It creates electrical signals which spread through both atria walls, making them contract in unison. Then impulses are delayed at the relay point, or AV node, where the atria empties completely before the ventricles contract. Finally, the muscle fibers called bundle branches and Purknje fibers send signals to the apex of the heart and throughout the ventricle. This creates powerful contractions sending blood into the large arteries.

17. Explain why blood flow through capillaries is substantially slower than it is through arteries and veins.

Courtney Connolly

By the law of continuity, the volume of flow per second must be constant over an entire pipe. The fluid must flow at a faster velocity as the cross-sectional area of the pipe narrows. Capillaries have a large total cross-sectional area because there are many more capillaries than arteries. This means that the velocity through the capillaries is much slower. It is beneficial that blood flow happens very slowly in the capillaries because it is the only place where substances can be transferred through the vessel wall from the blood to the interstitial fluid. The blood speeds up again after leaving the capillaries. Because there is a smaller cross-sectional area in arteries and veins, the blood flows at a faster velocity (no substantial exchange of substances takes place here like it does in the capillaries).

18. Define blood pressure and describe how it is measured. Isabelle Haller
The blood pressure is the pressure of the blood within the arteries. It is produced primarily by the contraction of theheart muscle. It's measurement is recorded by two numbers. The first (systolic pressure) is measured after the heart contracts and is highest. The second (diastolic pressure) is measured before the heart contracts and lowest. A blood pressure cuff is used to measure the pressure. Elevation of blood pressure is called "hypertension".
A cuff that inflates is wrapped around your upper arm. A tube leads out of the cuff to a rubber bulb. Another tube leads from the cuff to a reservoir of mercury at the bottom of a vertical glass column. Whatever pressure is in the cuff is shown on the mercury column. The mercury is held within a sealed system – only air travels in the rubber tubing and the cuff. Air is then blown into the cuff and increasing pressure and tightening is felt on the upper arm. The doctor puts a stethoscope to your arm and listens to the pulse while the air is slowly let out again. The systolic pressure is measured when the doctor first hears the pulse. This sound will slowly become more distant and finally disappear. The diastolic pressure is measured from the moment the doctor is unable to hear the sound of the pulse. The blood pressure is measured in terms of millimetres of mercury (mmHg).

19. Explain how peripheral resistance and cardiac output affect blood pressure.

Marta Gosiewski
Cardiac output is the volume of blood being pumped by the heart, in particular by a left or right ventricle in the time interval of one minute. Peripheral resistance is the force against blood flow. As peripheral resistance increases, cardiac output and blood flow decrease and blood pressureincreases. Lower resistance increases blood flow, decreases blood pressure and increases cardiac output.

20. Explain how blood returns to the heart even though it must sometimes travel from the lower extremities against gravity.

Emma Leister
In order to transfer blood from the lower extremities to the heart, the blood has to be pumped up through the veins. Since the blood has to move against gravity, there are several valves in the veins that prevent the blood from flowing backwards. There are muscle contractions that sqeeze the veins, forcing the blood upward. Different blood pressure levels in the veins are also crucial in blood circulation. These levels have to be altered when a person stands up and sits down. When a human stands up, it takes an extra 27 mm/Hg to move the blood from the lower extremities upward so it can reach the heart through the inferior vena cava.

external image legvalves.gif

21. Explain how blood flow through capillary beds is regulated.

Bryan Mathis
Blood flow through capillary beds is able to occur due to their thin walls. These walls allow oxygen to flow out of the blood cells and into the surounding cells where they are needed. The overall blood flow of these areas changes depending on the action, condition, and stress of the body. Main blood flow comes from the heart and uses the same pumping system that is used by the rest of the body. As the heart beats, it contracts pushing blood through every artery, vein, and capillary throughout the system.
However, capillaries are often far from the heart and are not able to continue at a constent flow from the heart's beating alone. The blood spreads out when it reaches the capillary beds causing a decrease in blood pressure in this area. In order to prevent a blood traffic jam, the hemoglobin in the red blood cells releases oxygen to the cells closest to the capillary wall. These cells in turn release nitric oxide, causing these cells to relax. The area around the capillary becomes less constricted allowing the blood to flow at a faster rate and increase the blood pressure back to its normal level. This process makes up for the ineffectiveness of the heart in these small, but spread out areas.

22) Explain how osmotic pressure and hydrostatic pressure regulate the exchange of fluid and solutes across capillaries.
Luke Heisinger

Capillaries are the smallest blood vessels found in the human body - only about 1 cell thick - and are porous enough that the fluid (or plasma) within them is in contact with the fluid outside of them. Because these fluids can exchange through the walls of the capillaries, Osmotic and Hydrostatic pressure regulate the exchange of these fluids.
Osmotic pressure exists whenever two solutions with differing solute concentrations interact and is caused as water always moves from the hypotonic to the hypertonic solution. Human blood found in the capillaries is hypertonic to the fluids found outside of the capillaries. So water is always trying to push its way into the blood vessel due to osmotic pressure. The pressure due to osmosis remains constant across the entire capillary, and based off of this pressure, certain solutes and fluids can or cannot cross the capillaries.
The Hydrostatic, or blood, pressure is an outward pressure caused by the blood that is pushing on the walls of the capillary as it runs through the capillary. Unlike Osmotic pressure, Hydrostatic pressure is not constant throughout the capillary as there is more pressure on the arteriole side because it is closer to the heart. The Hydrostatic pressure of the blood pushing out on the venule side is greater at the arteriole end than the osmotic pressure pushing in. So, the net pressure on all fluids at the arteriole side is outward. On the venule side, the Hydrostatic pressure of the blood pushing out is less than the osmotic pressure pushing in causing the net pressure to be inward. As a result this difference in pressure will allow the arteriole side to exchange different particles then the venule side.

Osmotic pressure (blue arrows for water)
Hydrostatic pressure (red arrows for blood).
24. (Paige Peterson) Describe the composition and functions of plasma.
Plasma is the material blood cells are suspended in. It is about 90% water but also contains proteins, such as fibrinogens and anitbodies, and dissolved ions (electrolytes). The proper functioning of muscles and nerves depends on the correct concentration of these ions. Plasma is responsible for transporting nutrients and hormones through the body and for removing waste such as carbon dioxide and bringing it to the lungs.
25. (Emma Culleton)
The erythrocyte membrane contains equal amounts of lipids and proteins. Membrane lipids are either phospholipids or neutral lipids and are asymmetrically arranged into a lipid bilayer two molecules thick. The amounts of cholesterol and phospholipids are responsible for the fluid properties of the erythrocyte membrane. Mutations in the membrane cholesterol-phospholipid ratio result in abnormal erythrocytes with decreased life span. Membrane proteins are also asymmetrically oriented within the lipid bilayer and can be divided into three functional sets: structural, catalytic and receptor proteins. Sprectrin and actin are the two main structural proteins that together form a submembranous cytoskeletal meshwork. Band 3, or the anion channel, is a major transmembranous protein involved in the transport of water and anions and is a carrier of the blood-group-I antigen. Glycophorin A, a sialic-acid-rich glycoprotein, is the major contact or receptor membrane polypeptide that also spans the lipid bilayer. The MN blood group determinants and possibly other biologic receptor sites have been localized on the extracellular portion of glycophorin A. At least 35 to 40 enzymes are confined to the membrane and play a vital role in the maintenance of normal structure and function of the erythrocyte.

26. List the five main types of white blood cells and generaly characterize their functions...

Stephanni Perini
White blood cells are also known as 'WBC's' or 'leukocytes'. These white blood cells belong to the human immune system, and they have the function of fighting infections that our body may be faced with. The white blood cells circulate within the body at various points, and if and when there is an infection, they are transported to that particular area, so that they may start their fight against whatever alien substance may have entered the body. There are five main types of white blood cells found within our body, and they are neutrophils, eosinophils, basophils, lymphocytes, monocytes. While neutrophils act as one of the more important defenses that our body has against infectious bacteria, eosonophils have the duty of killing parasites, and play a major role in fighting allergens. Basophils perform the function of releasing histamine and heparin, while lymphocytes virtually direct the body's immune system. Monocytes enter the tissue, where they multiply to fight infections.

27. Relate the structure of platelets to their functions. (Sarah Nelson

Platelets are purposed to clot or stop the flow of blood after a cut or injury to blood vessels. Platelets are produced by large bone marrow cells called megakaryocytes. They are pieces of cells and can circulate easily to help blood clot. Platelets are suspended in liquid called plasma along with other cells to make up whole blood. Although they are only small pieces their form helps blood clot easily. This form starts with proteins on the surface that allow platelets to stick to each other and stick to breaks in cell walls (important for clotting blood). They also have granules that can secrete other proteins to hasten blood clotting. Platelets also have muscle-like proteins to change shape if flow is slowed and are shaped like a plate. The fibers on the interior of the vessel wall attract the platelets and help the clot thicken. When a break in the blood vessels occurs, such as in a paper cut, they change shape and become round and elongate. The long filaments are what attach to the wall and clot.


Outline the formation of erythrocytes from stem cells to their destruction by phagocytic cells.

The life cycle of a red blood cell.
All blood cells, including red blood cells (erythrocytes), white blood cells (leukocytes), and platelets first form in the bone marrow.
They all develop from pluripotent stem cells which inhabit the bone marrow, particularly in the ribs, vertebrae, breastbone, and pelvis.
A negative-feedback mechanism, sensitive to the amount of oxygen reaching the tissues via the blood, controls erythrocyte production. If the tissues do not receive enough oxygen, the kidney converts a plasma protein to a hormone called erythropoietin, which stimulates production of erythrocytes. If blood is delivering more oxygen than the tissues can use, the level of erythropoietin is reduced, and erythrocyte production slows.
Afterwards, erythrocytes circulate in the bloodstream for approximately 120 days, or 3 to 4 months. These worn-out blood cells are destroyed in the liver and spleen and recycle parts of the cells. Enzymes digest the cells, and new macromolecules are made from the old cells. Many of the iron atoms taken from the hemoglobin of old cells are rebuilt into new hemoglobin molecules of new red blood cells.

37. Describe the advantages and disadvantages of air as a respiratory medium and explain how insect tracheal systems are adapted for efficient gas exchange in a terrestrial environment.

Courtney Connolly

Air has a higher concentration of oxygen than water. O2 and CO2 diffuse faster in air than they do in water. This means that more O2 is brought to the “respiratory surface” faster and CO2 is taken away faster so not as much ventilation is needed by the animal. When ventilation is needed, air is much lighter so it is easier to ventilate for terrestrial animals. Also, a significantly less amount of air can be used in place of water to get the same amount of oxygen.

However, the respiratory surface must be moist and large. This means that it loses water through evaporation. Insects have adapted to this disadvantage. They have a respiratory surface that is folded into their body. Air tubes reach from the outside to almost every cell (where gas exchange occurs). This makes the respiratory system easily accessible to all cells so their open circulatory system does not have to transport O2 and CO2. Small insects use diffusion through the trachea to power cell respiration while larger insects use rhythmic body motions to ventilate their system. Insects in flight use their fast moving (contracting) muscles to pump the air through their system.

Lungs are a respiratory surface but need the circulatory system to transport gases between it and the other parts of the body. Some vertebrates have small lungs or do not have lungs. They mostly use diffusion for exchange of gases. All mammals and birds along with most reptiles use mostly lungs for exchange of gases. Lungs have adapted to match the organisms’ metabolic rate (and rate of gas exchange). Endotherms have a larger “exchange surface” than ectotherms.

Objectives 29 - 47 here

29: Outline the sequence of events that occur during blood clotting and explain what prevents spontaneous clotting in the absence of injury.

Patrick Doran

When an injury occurs, there is a complex chain of reactions that eventually leads to a blood clot. This reaction begins with the release of clotting factors from platelets that trigger a chain of reactions that convert the plasma protein called fibrinogen into its active form, fibrin. Fibrin aggregates into threads that end up forming the framework of a clot. One reason spontaneous clots don't usually occur is because the protein that makes up clots, Fibrin is usually in its inactive form, fibrinogen. It is only converted into fibrin when clotting factors are released due to injury. Anticlotting factors are also normally present to prevent the spontaneous formation of a clot.

30. Distinguish between a heart attack and a stroke; antherosclerosis and arteriosclerosis; and low-density lipoproteins (LDLs) and high density lipopreteins (HDLs). (A.Gosiewski)

-> A heart attack and a stroke are both common cardivascular diseases. More specifically, a heart attack results from oxygen rich blood not being able to enter the heart because of blockage in one ore more coronary arteries. However, a stroke occurs when there is a blockage in arteries leading to the brain. Therefore oxygen rich blood is not able to reach the brain.

-> Antherosclerosis is a chronic cardivascular disease. This disease cause the growth of plaque on the inner walls of arteries. The build up of plaque changes the construction of the smooth muscle in the arterie; there are large amounts of lipids and cholesteral in the smooth muscle. Another disease is present when the plaque hardens because of calcium, known as arterioslerosis. Plaque is able to adhere more easily to the arterie walls which can create more serious problems.

-> LDLs are known as "bad cholesteral" because the cholesteral is deposited in the arteries. HDLs are known as good cholesteral because they can help reduce cholesteral deposits. Exercise and healthy dieds can increase HDLs while smoking and bad health habits can increase LDLs.

31. List the factors that have been correlated with an increased risk of cardiovascular disease (Veektor)

The most dangerous events related to cardiovascular diseases would be the heart attack or the stroke. Heart attacks occur when cardiac muscles do not have enough oxygenated blood flowing to them and thus result in the death of the muscle. When a similar lack of oxygen occurs in the brain, nervous tissues begin to die and thus result in a stroke. An explanation to the occurring of these events is a chronic disease called atherosclerosis. This causes plaque to build up on the inner walls of arteries, which narrows the amount of blood flow possible. Sometimes, calcium deposits harden this plaque creating an even larger problem called arteriosclerosis. As these diseases progress, the risk factor increases greatly as well. Arteries will become more clogged and rigid which increases the chance of a thrombus (clot) or an embolus (transported clot from the bloodstream) which in turn creates heart attacks and strokes. Hypertension also increases all of these factors because it destroys artery linings which promotes plaque build up. High blood pressure is usually a sign of atherosclerosis and they promote each other. In some cases, these diseases are genetic, but they can also be caused by other factors. These include smoking, lack of exercise, animal fat consumption, and high cholesterol. Cholesterol has two forms: low-density lipoproteins (LDL) and high-density lipoproteins (HDL). LDLs generally deposit cholesterol in arterial plaques while HDLs may actually reduce cholesterol deposition. Exercise increases the amount of HDLs and smoking increases LDLs.

33. Describe the general requirements for a respiratory surface and list the variety of respiratory organs that have adapted to meet them. (Nicole Saitta)

A respiratory surface is the part of an animal where gases are exchanged with the environment. Oxygen diffuses in and carbon dioxide diffuses out. The gases can only diffuse if they are first dissolved in water and there is a concentration gradient between the two sides of the membrane. As well, the surface must be large enough to absorb O2 and expel CO2. Unicellular organism, such as protozoa, exchange gases over their entire surface area. Sponges and flatworms have body structures in which plasma membrane of each body cell contacts the outside environment and can function in exchange. In more complex body systems, respiratory surfaces are isolated from the environment, so the respiratory surface is a single cell layer that separates the respiratory medium from blood or capillaries. It must be extensively branched for there to be sufficient surface area for gas exchange. Earthworms and some amphibians use outer skin as respiratory organ, so they must live in water or damp places. Three respiratory organs are gills, tracheal systems, and lungs. Gills are outfoldings of body surface specialized for gas exchange in aquatic animals. Tracheal systems are a system of branched, chitin-lined tubes that infiltrate the body and carry oxygen directly to cells (mostly found in insects). The lungs are highly vascularized invaginations that connect to the atmosphere by narrow tubes that are found in terrestrial vetebrates, land snails, and spiders.

34.Describe respiratory adaptations of aquatic animals. Giselle Ilada

Gills are an important respiratory adaptation of aquatic animals. Though they vary among animals, the total surface area of the gills is usually greater than that of the rest of the body. Gills are effective in the process of ventilation, which increases the flow of the respiratory medium over the respiratory surface. Without it, high carbon dioxide levels can form around the gill during gas exchange. Also, the arrangement of capillaries makes it possible for oxygen to be transferred to blood. This is called countercurrent exchange.

38. For the human respiratory system, describe the movement of air through air passageways to the alveolus, listing the structures that air must pass through on its journey. -Isabelle Haller
Air first enters through the nostrils and enters into the nasal cavity and then the larynx. THe air goes past the vocal cords in the larynx and passes into the trachea. The trachea seperates into two bronci. Then, the air thats in the lung branches from the bronchus. They lead to fine bronchioles. THere is a cluster of alveoli air sacs at the end of the bronchioles. Gas exchange occurs across the thin epithelia of the lungs millions of alveoli.

39. Compare positive and negative pressure breathing. Explain how respiratory movements in humans ventilate the lungs.

Negative pressure is caused in humans by the contraction of the diaphragm, and the relaxation of intercostal muscles, increasing the volume of the thoracic cavity, which the lungs expand to fill. When the pressure within the lungs stays the same and air moves freely in and out of the lungs, negative pressure is applied. Positive pressure breathing is forcing air into the lungs to improve any pressure issues. Positive pressure breathing refers to using a specific device to regulate breathing. This is typically done when certain medical conditions cause difficulties with breathing. Air is pushed through a facial mask or an airway pressure system. The air and gases within the lungs are then balanced and the breathing can return to normal. Positive pressure breathing can help to eliminate life-threatening situations that can arise from not enough pressurewithin the lungs. Respiratorymuscles mediate the movement of air into and out of the body. Ventilation of the lungs in humans is carried out by the muscles of respiration, which explains why the respiratory system includes many mechanisms.

40. Distinguish between tidal volume, vital capacity, and residual volume.

Emma Leister

Tidal volume is the lung volume that represents the volume of air inhaled or exhaled during normal, resting breathing. The average tidal volume for a healthy adult is around .5 liters. This number can be adjusted according to the height, health, and altitude of the person. Taller people who don't smoke and live at high altitudes have a geater lung capacity, and therefore, a greater tidal volume. Vital capacity is the maximum amount of air a person can expel from the lungs after a maximum inspiration. A spirometer measures vital capacity, and it can be used to detect lung disease. A normal adult has a vital capacity between 3-5 liters, but this can change based on age, sex, height, weight, and ethnicity. The residual volume is the amount of gas remaining in the lung at the end of a maximal exhalation. The average value of residual volume is around 1.2 for a healthy adult.

41. Explain how the respiratory system of birds is different from that in mammals.

Bryan Mathis

The Respiratory systme in birds is a little different from the respiratory system in mammal

Bird Respiratoy System (Avian Respiratory System)

external image ill_bird_airsacs.gif

Mammal Respiratory System

external image humrespsys_1.gif

While the bird respiratory system has the same parts of the respiratory system of mammals, it has the addition of nine air sacks connected near the lungs. The bird's respiration system is known as uniderectional flow of air. This means that the air that is inhaled never mixes with the air that is exhaled. The bird accomplished this by using the air sacks conected to its lungs. These air sacks are used to store the air from the lungs for a short while after the bird inhales, and release the air without reentering the lungs when the bird exhales. This allows new air to enter the lungs without the interferance of the old air. Mammals on the other hand have a biderectional flow of air in which the new and old air are mixed together in the lungs, creating a less efficiant form of breathing. The design of the bird's respiratory system increases the oxygen in the lungs, allowing more of it to diffuse into the blood. Because of this, birds have a more effecient respiratory system than mammals.

42) Explain how breathing is controlled.
Luke Heisinger

Breathing is controlled by the brain stem and which is responsible for maintaining homeostasis, specifically regarding the pH balance of our blood. The average human being has a blood pH of around 7.3, which is slightly alkaline. Breathing is responsible for regulating the amount of oxygen vs. carbon dioxide in the blood stream as we are exchanging used carbon dioxide for oxygen in the lungs. As our cells use oxygen and create carbon dioxide, the concentration in our blood stream increases, and makes the blood more acidic. In an effort to maintain homeostasis, the body forces you to exhale and provide oxygen, which allows the blood to return to its normal state. As a result, breathing is controlled by the pH levels due to carbon dioxide concentration in the blood stream.

Objectives 12 and 32

Abby Schwarz

Objective 12:
Define heart murmur and explain its cause.
A heart murmur is an indication of a problem with the valves of the heart. This valve problem causes the altered sound of the hissing of blood as it squirts backward through the valve. Some people are born with heart murmurs, other valves are damaged by infection. Most heart murmurs aren't serious enough to warrant surgery

Objective 32:
Define gas exchange and distinguish between a respiratory medium and a respiratory surface.

Gaseous exchange is the intake of Oxygen and the expulsion of Carbon dioxide. In the capillaries of the alveoli, oxygen travels due to the concentration gradient into those capillaries. Carbon dioxide is then expelled from those capillaries. The respiratory medium is air for animals and water for fish. It is basically the substance through with living animals receive their oxygen. The respiratory surface is where the gaseous exchange takes place. The oxygen and carbon dioxide move across the respiratory surface entirely by diffusion.
Scott Ferraro
Objective 16:
Arteries are blood vessels that carry the oxygenated blood away from the heart. They vary in their size, depending on their position in the body, and how far away from the heart they are. The structure of an artery is three layers of tissue. As arteries branch into organs they divide into smaller vessels called arterioles. They also help to push the rapid flow of blood when the ventricles are relaxed and the heart is refilling. As the arteries become smaller the tunica media consists almost entirely of smooth muscle. These cannot stretch as much as the larger arteries. They still pass a small amount of blood through them, directing it elsewhere in the circulation. These small arteries are known as arterioles. Arteries contain about 20% of blood at any one time. You can feel your pulse in an artery.

Tunica adventria (outer layer of fibrous tissue)
Tunica media (middle layer of smooth muscle & elastic tissue)
Tunica intima (inner lining of endothelium)

Veins are the blood vessels that carry deoxygenated blood back to the heart. The walls of the veins are thinner than the arteries, but they do still have the same three layers in them. You will find less muscle and elastic tissue in the tunica media. Some veins have valves in them to ensure the flow of blood travels to the heart, and not backwards. The smallest of the veins (furthest away from the heart) are known as venules. Veins contain about 75% of blood at ant time. There is lower pressure in the vein, compared to that of the arteries, so no pulse can be felt.

Capillaries are the smallest blood vessels in the body. Their structure consists of just a single layer of endothelial cells. Water and other small-molecule substances can pass through this wall. Capillaries act as a link between arteries and veins. No valves can be found in the capillaries. The exchange of blood and tissue takes place at the capillary bed. Capillaries contain about 5% of blood at any time, and no pulse can be felt in one.

Objective 36
Countercurrent exchange is a mechanism occurring in nature and mimicked in industry and engineering, in which there is a crossover of some property, usually heat or some component, between two flowing bodies flowing in opposite directions to each other. The flowing bodies can be liquids, gases, or even solid powders, or any combination of those.

45. (Emma Culleton)
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In its basic form, the oxyhemoglobin dissociation curve describes the relation between the partial pressure of oxygen (x axis) and the oxygen saturation (y axis). Hemoglobin's affinity for oxygen increases as molecules of oxygen bind. More molecules bind as the oxygen partial pressure increases until the maximum amount that can be bound is reached. As this limit is approached, very little additional binding occurs and the curve levels out as the hemoglobin becomes saturated with oxygen. Hence the curve has an S-shape. At pressures above about 60 mmHg, the standard dissociation curve is relatively flat, which means that the oxygen content of the blood does not change significantly even with large increases in the oxygen partial pressure. To get more oxygen to the tissue would require blood transfusions to increase the hemoglobin count, or supplemental oxygen that would increase the oxygen dissolved in plasma.

46. Describe how carbon dioxide is picked up at the tissues and deposited into the lungs
stephanni perini

CO2 is carried in blood in three different ways. The most important is in the form of bicarbonate ions through the reaction
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H20 + CO2 ==> H+ + HCO3-
This reaction is facilitated in blood by the enzyme carbonic anydrase which is present in red blood cells.
Nearly all bicarbonate is made within the red blood cell. HCO3- enters the plasma in exchange for Cl- ions via an ion transporter on the red blood cell membrane. The exchange of bicarbonate and chloride ions across the membrane is called the "chloride shift".
CO2 is also carried in chemical combination with hemoglobin, upon which it binds at different sites to O2. The shape of the CO2 dissociation curve for hemoglobin is very different from the O2 curve. In fact, it is nearly linear over the arterial-venous PCO2 range.
CO2 is also quite soluble in water (much more so that O2), so that a third significant means of CO2 transport in the blood is by simple solution.

47. Describe respiratory adaptations of diving mammals and the role of myoglobin. (Sarah Nelson)

======Diving mammals such as seals, whales, and dolphins have developed the diving reflex. This reflex is activated when a mammal's face is submerged in cold water and cannot occur when limbs are submerged. It is possible for humans to do this to some degree as well. This reflex means that their heart rate decreases as well as their oxygen consumption. Because of this, they can dive to great depths with their reduced oxygen consumption and stay underwater for longer. These diving animals have a higher level of myoglobin because the higher levels allow them to hold their breath for longer. The myoglobin can prevent the binding of CO2 within the body. The myoglobin is protein that exists in the muscles and is abundant because it allows muscles to work well in low oxygen states. It is structurally similar to hemoglobin and bonds with oxygen to store and facilitate the transfer of oxygen.======